Chamfered corner crackstop for an integrated circuit chip

ABSTRACT

A corner crackstop is formed in each of the four corners of an integrated circuit (IC) chip, in which the corner crackstop differs structurally from a portion of the crackstop disposed along the sides of the IC chip. Each corner crackstop includes a plurality of layers, formed on a top surface of a silicon layer of the IC chip, within a perimeter boundary region that comprises a triangular area, in which a right angle is disposed on a bisector of the corner, equilateral sides of the triangle are parallel to sides of the IC chip, and the right angle is proximate to the corner relative to a hypotenuse of the triangle. The plurality of layers of the corner crackstop include crackstop elements, each comprising a metal cap centered over a via bar, in which the plurality of layers of the corner crackstop is chamfered to deflect crack ingress forces by each corner crackstop.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention claims the benefit under 35 U.S.C. §120 as adivisional of presently pending U.S. patent application Ser. No.13/276,383 filed on Oct. 19, 2011, the entire teachings of which areincorporated herein by reference.

BACKGROUND

The exemplary embodiments generally relate to a corner crackstop and amethod of making the corner crackstop in each of the four corners of anintegrated circuit (IC) chip, in which the corner crackstop differsstructurally from a portion of the crackstop disposed along the sides ofthe IC chip. More specifically, each corner crackstop includes aplurality of layers disposed between a silicon layer and a finalpassivation layer of the IC chip. The plurality of layers of the cornercrackstop include crackstop elements, each comprising a metal capcentered over a via bar. Yet more specifically, the plurality of layersof the corner crackstop is chamfered to deflect crack ingress forces byeach corner crackstop.

DESCRIPTION OF RELATED ART

In manufacturing semiconductor devices, a number of integrated circuits(ICs) are simultaneously prepared on a semiconductor wafer byconventional photolithography techniques. The ICs, which are rectangularin shape, are disposed in a grid pattern on the semiconductor wafer.Each of the four sides of each individual IC is adjacent to a dicinglane. The individual ICs are singulated by dicing the wafer along thedicing lanes with either a saw or laser to form IC chips or dies.

An individual IC chip includes an active region that comprises activeand passive electrical devices, which provide the IC's functionality,and a perimeter boundary region that is adjacent to the dicing lanes.The active and passive electrical devices are formed within thesemiconductor layer of the active region, which is located behind acrackstop that separates the active region from the perimeter boundaryregion. The IC chip, including both the active region and the perimeterboundary region, is covered by a plurality of metallization layers, eachof the metallization layers including a patterned intermetallicdielectric layer that includes vias and an overlaying patterned metallayer. Within the active region, each of the plurality of metallizationlayers includes electrical contacts, formed within the vias that contactthe overlying patterned metal layer. The patterned metal layer formsinterconnect with the electrical contacts to the underlying active andpassive electrical devices of the semiconductor layer.

Upon dicing, the IC chip is subject to crack ingress forces along itssides and greater crack ingress forces at the corners. Conventionally, acrackstop is formed parallel to the rectangular perimeter of the IC chipto prevent the crack ingress forces from delaminating or cracking theelectrical devices and the metallization layers of the active region. Acrackstop includes a plurality of layers formed on the silicon layer ofthe perimeter boundary region, each layer being formed by processesidentical to those used in forming the metallization layers of theactive region of the IC chip.

FIG. 1 illustrates a top view, in the x-y plane, of a conventionalcrackstop 150, disposed on an IC chip 110, in which an overlying finalpassivation layer is removed to view crackstop 150. The crackstop 150includes portions that are beveled in the corner regions of the IC chip110 to provide greater protection to the active region 160 from thegreater ingress crack forces at the corners. The portions of thecrackstop 150 that parallel the sides of the IC chip 110 and thoseportions of the crackstop 150 that are beveled in the corner regionsinclude the same plurality of layers and the same structural elementswithin each layer.

FIG. 2 illustrates, in greater detail, a top view of corner region A(dotted lines) of FIG. 1. Referring to FIG. 2, a beveled portion of thecrackstop 150 defines a hypotenuse, H, in the x-y plane, of a triangulararea that is further defined by two right-angled sides (dotted lines),which extend from those portions of the crackstop 150 that parallel thesides of the IC chip 110. This triangular area, which forms theperimeter boundary region of each of the four corner regions of IC chip110, provides greater protection to the active region 160 from thegreater ingress crack forces generated at the corners, when compared toa crackstop that parallels the rectangular perimeter of an IC chip. InFIG. 2, a construction line, C-C′, in the x-y plane, extends from acorner of the IC chip 110 to cross the beveled portion of the crackstop150 at a right angle.

Referring to FIGS. 3A and 3B, FIG. 3A illustrates a cross-section ofcrackstop 150 in a plane defined by the z-axis and construction lineC-C′, as viewed along the hypotenuse, H, shown in FIG. 2, while FIG. 3Billustrates another cross-section of crackstop 150 in a plane defined bythe z-axis and the hypotenuse, H, as viewed from C of the constructionline C-C′, i.e., from the corner of the IC chip 110 toward the center ofthe IC chip 110. Crackstop 150 is formed on the silicon layer 315 of theIC chip 110 by, for example, four layers, 301-304, each layer comprisingcrackstop elements that include a metal cap 320 centered above a via bar310. The via bar 320 differs from a conventional contacting cylindricalvia by having a length, oriented along H, that exceeds its width.

Processes identical to those that form the metallization layers of theactive region 160 of the IC chip 110 simultaneously form each layer ofcrackstop 150. Each metallization layer of the active region 160comprises a patterned metal layer, which corresponds to the metal cap320 of a layer of crackstop 150, and electrical contacts, formed withinthe intermetallic dielectric layer, which correspond to the via bar 320.These processes of simultaneously forming the metallization layers ofthe active region 160 and the layers of crackstop 150 include:deposition of an intermetallic dielectric on a silicon substrate in theactive region 160 and the perimeter boundary region; patterning theintermetallic dielectric to form vias in the active region 160 and viabars in the perimeter boundary region; filling the vias with metal toform electrical contacts in the active region 160 and the via bars withmetal to form part of a crackstop element in the perimeter boundaryregion; and depositing and patterning a metal layer over the electricalcontacts and intermetallic dielectric to form interconnects between theelectrical contacts in the active region 160 and over the via bars andintermetallic dielectric to form overlying metal caps on the via bars inthe perimeter boundary region.

In contrast to the electrical contacts and the patterned metalinterconnects of the active region 160, the metal caps 330 and via bars320 of the crackstop 150 do not electrically contact any of the activeor passive electrical devices in the active region 160 of the IC chip110. Instead, the metal caps 330 and via bars 320 of the crackstop 150perform a mechanical function of preventing the ingress of crack forcesto the active region 160 located behind crackstop 150 of IC chip 110.

Referring to FIG. 3B, each metal cap 330 and via bar 320 of the beveledportion of the crackstop 150 extends the length of the hypotenuse, H,and joins the metal caps and via bars, at an approximately 45° angle, ofthe metal cap and via bar structures of those portions of the crackstop150, which parallel the sides of the IC chip 110. Thus, the verticallyaligned crackstop elements of the beveled portions of the crackstop 150,i.e., a metal cap 330 centered over a via bar 320, are the same as thosevertically aligned crackstop elements, i.e., a metal cap centered over avia bar, of those portions of the crackstop 150, which are parallel tothe sides of the IC chip 110. Viewed from C of the C-C′ constructionline shown in FIG. 2, the metal caps 330 and via bars 320 of the layersof the beveled portion of the crackstop 150, illustrated in FIG. 3B,form a vertical metal “wall”, between the silicon layer 305 and thefinal passivation layer 335 that prevents the ingress of crack forces inthe corner region. Those areas (dotted lines) to the right and left ofthe metal caps 330 and the via bars 320 of FIG. 3B, represent the samemetal cap and via bar structures of those portions of the crackstop 150,which parallel the sides of the IC chip 110. FIG. 3A shows that thisvertical metal “wall” comprises a plurality of layers, each layerincluding crackstop elements of a metal cap 330 centered above a via bar320, where the metal caps 330 and via bars 320 are vertically alignedamong all of the layers 301-304.

Although the top view of FIG. 2 shows the beveled portion ofconventional crackstop 150 comprising a rectilinear structure orientedalong the angle of the hypotenuse, H, an outward-facing surface of therectilinear angled structure can be “broken up” into a zigzag pattern402 of structural elements, as shown in FIG. 4A. It is thought that thezigzag pattern 402 helps to “break up” the ingress of crack forces intothe corner region. The zigzag pattern 402 can be extended to thoseportions of the crackstop, which are parallel to the sides of the ICchip. Referring to FIG. 4A, individual crackstop elements, eachincluding a metal cap centered over a via bar that is oriented parallelto a beveled portion of the corner crackstop, can form zigzag pattern402. Alternatively, a semiconductor manufacturing process mayapproximate a rectilinear angled structure by forming a right-angledzigzag pattern of crackstop elements along the x-y axes of the IC chip,as shown in FIG. 4B, to form an outward-facing surface of the cornercrackstop. Referring to FIG. 4B, individual rectangular corner crackstopelements 430, each including a metal cap centered over a via bar that isoriented along the x-y axes of the IC chip, can form right-angled zigzagpattern 404, which approximates the rectilinear beveled portion of acorner crackstop. Again, it is thought that the zigzag pattern 404 helpsto “break up” the ingress of crack forces into the corner region.

There remains a need to maximize crack stopping robustness withoutdecreasing the active region of an IC chip, which is protected by aconventional crackstop having beveled portions in the corner regions,where the same vertically aligned crackstop elements are formed in thebeveled portions of the conventional crackstop and in those portions ofthe conventional crackstop that are parallel to the sides of the ICchip.

SUMMARY

In view of the foregoing, an exemplary embodiment of the inventiondisclosed herein provides a corner crackstop including: a plurality of nlayers formed on a silicon layer of an integrated circuit (IC) chipwithin a perimeter boundary region of a corner of the IC chip, eachlayer including a number of crackstop elements, each crackstop elementhaving a same width and including a metal cap centered on a via bar. Theperimeter boundary region is disposed on a top surface of the siliconlayer and comprises a triangle, a right angle of the triangle beingdisposed on a bisector of the corner, equilateral sides of the trianglebeing parallel to sides of the IC chip, and the right angle beingproximate to the corner relative to a hypotenuse of the triangle. Afirst crackstop element of a first layer is disposed proximately to theright angle of the triangle, oriented in parallel to the hypotenuse, andhas a smallest length limited by the equilateral sides. A secondcrackstop element of the first layer adjoins the first crackstop elementand has a greater length limited by the equilateral sides, and an nthcrackstop element of the first layer adjoins an (n−1)th crackstopelement and has a greatest length limited by the equilateral sides. Afirst crackstop element of a second layer is vertically aligned over thesecond crackstop element of the first layer and has the greater length,and an (n−1)th crackstop element of the second layer is verticallyaligned over the nth crackstop element of the first layer and has thegreatest length, and a single crackstop element of an nth layer isvertically aligned over a second crackstop element of an (n−1)th layerand has the greatest length.

Another exemplary embodiment disclosed herein provides a cornercrackstop including: a plurality of n layers formed on a silicon layerof an integrated circuit (IC) chip within a perimeter boundary region ofa corner of the IC chip, each layer including a number of crackstopelements, each crackstop element having a same width and including atleast one metal cap disposed on a via bar of width, w. The perimeterboundary region is disposed on a top surface of the silicon layer andcomprises a triangle, a right angle of the triangle is disposed on abisector of the corner, equilateral sides of the triangle are parallelto sides of the IC chip, and the right angle is proximate to the cornerrelative to a hypotenuse of the triangle. A crackstop element of a firstlayer is disposed proximately to the right angle of the triangle,oriented in parallel to the hypotenuse, and has a smallest lengthlimited by the equilateral sides. A crackstop element of a second layeris disposed more distally from the right angle than the crackstopelement of the first layer by a distance of less than ½ w, along thebisector, oriented in parallel to the hypotenuse, and has a greaterlength limited by the equilateral sides. A crackstop element of an nthlayer is disposed more distally from the right angle than the crackstopelement of the (n−1)th layer by the distance along the bisector,oriented in parallel to the hypotenuse, and has a greatest lengthlimited by the equilateral sides.

Yet another exemplary embodiment disclosed herein provides a method ofmaking a corner crackstop including forming a plurality of n layers on asilicon layer of an integrated circuit (IC) chip within a perimeterboundary region of a corner of the IC chip, each layer including anumber of crackstop elements, each crackstop element having a same widthand including at least one metal cap centered on a corresponding atleast one via bar, the at least one via bar having a width, w. Theperimeter boundary region is defined on a top surface of the siliconlayer that comprises a triangle, a right angle of the triangle beingdisposed on a bisector of the corner, equilateral sides of the trianglebeing parallel to sides of the IC chip, and the right angle beingproximate to the corner relative to a hypotenuse of the triangle. Themethod further includes: forming a crackstop element of a first layerdisposed proximately to the right angle of the triangle, oriented inparallel to the hypotenuse, and having a smallest length limited by theequilateral sides. The method further includes forming a crackstopelement of a second layer disposed more distally from the right anglethan the crackstop element of the first layer by one of: a distanceequal to the width of a crackstop element, and a distance less than ½ wof the via bar, along the bisector, being oriented in parallel to thehypotenuse, and having a greater length limited by the equilateralsides. The method further includes forming a crackstop element of an nthlayer disposed more distally from the right angle than a crackstopelement of a (n−1)th layer by the one distance, along the bisector,being oriented in parallel to the hypotenuse, and having a greatestlength limited by the equilateral sides.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments herein will be better understood from the followingdetailed description with reference to the drawings, which are notnecessarily drawn to scale and in which:

FIG. 1 is a schematic diagram illustrating a top view of conventionalcrackstop on an integrated circuit (IC) chip in the related art;

FIG. 2 is a schematic diagram illustrating, in more detail, a top viewof a beveled corner region of the conventional crackstop of FIG. 1 inthe related art;

FIG. 3A is a schematic diagram illustrating a cross-section viewed alongthe hypotenuse, H, of the beveled corner region of the conventionalcrackstop of FIG. 2 in the related art;

FIG. 3B is a schematic diagram illustrating another cross-section viewedfrom C of the construction line C-C′, of the beveled corner region ofthe conventional crackstop of FIG. 2 in the related art;

FIG. 4A is a schematic diagram illustrating a top view of a beveledportion of a conventional crackstop, including crackstop elements thatform a zigzag pattern parallel to the beveled portion in the relatedart;

FIG. 4B is a schematic diagram illustrating a top view of a beveledportion of a conventional crackstop, including crackstop elements thatare oriented parallel to the x-y axes of the IC chip and form a zigzagpattern, which approximates the orientation of the beveled portion inthe related art;

FIG. 5 is a schematic diagram illustrating a top view of a cornercrackstop on an IC chip in an exemplary embodiment;

FIG. 6A is a schematic diagram illustrating a cross section viewed alongthe hypotenuse, H, of a corner region including the corner crackstop ofFIG. 5 in the exemplary embodiment;

FIG. 6B is a schematic diagram illustrating another cross section viewedfrom C of the construction line C-C′, of a corner region including thecorner crackstop of FIG. 5 in the exemplary embodiment;

FIG. 7 is a schematic diagram illustrating a top view of a cornercrackstop on an IC chip in another exemplary embodiment;

FIG. 8A is a schematic diagram illustrating a cross section viewed fromC of the construction line C-C′, of a corner region including the cornercrackstop of FIG. 7 in the another exemplary embodiment;

FIG. 8B is a schematic diagram illustrating another cross section viewedalong the hypotenuse, H, of a corner region having a single chamferedstructure for the corner crackstop of FIG. 7 in the another exemplaryembodiment;

FIG. 9 is a schematic diagram illustrating a cross section viewed alongthe hypotenuse, H, of a corner region having multiple chamferedstructures for a corner crackstop, similar to that of FIG. 7, in anotheralternative exemplary embodiment; and

FIG. 10 is a flowchart illustrating a method of making a cornercrackstop on an IC chip in an exemplary embodiment.

DETAILED DESCRIPTION

The exemplary embodiments of the invention and the various features andadvantageous details thereof are explained more fully with reference tothe non-limiting exemplary embodiments that are illustrated in theaccompanying drawings and detailed in the following description. Itshould be noted that the features illustrated in the drawings are notnecessarily drawn to scale. Descriptions of well-known materials,components, and processing techniques are omitted so as to notunnecessarily obscure the exemplary embodiments of the invention. Theexamples used herein are intended to merely facilitate an understandingof ways in which the exemplary embodiments of the invention may bepracticed and to further enable those of skill in the art to practicethe exemplary embodiments of the invention. Accordingly, the examplesshould not be construed as limiting the scope of the exemplaryembodiments of the invention.

As described above, there remains a need to maximize crack stoppingrobustness without decreasing the active region of an IC chip, which isprotected by a conventional crackstop having beveled portions in thecorner regions, where the same vertically aligned crackstop elements areformed in the beveled portions of the conventional crackstop and inthose portions of the conventional crackstop that are parallel to thesides of the IC chip.

FIG. 5 illustrates a top view, in the x-y plane, of an exemplaryembodiment of a corner crackstop 500 in a corner region of an IC chip510, where an overlying final passivation is removed. In the exemplaryembodiment, the corner crackstop may comprise, for example, four steppedlayers 501-504. The first layer of the corner crackstop is formed on thesilicon layer of the IC chip 510. The number of layers of the cornercrackstop equals the number of metallization layers formed within theactive region of the IC chip 510 and spans the height between theunderlying silicon layer and the final passivation layer of the IC chip510. In various embodiments, the number of layers, n, in the cornercrackstop may range from 3 to 12.

Referring to FIG. 5, an exemplary embodiment of a corner crackstop 500may be formed within a triangular area of the perimeter boundary region,indicated by the dotted lines, which is proximate to a corner of the ICchip 510. The triangular area, which is disposed on a top surface of thesilicon layer of the IC chip, may be defined by a right angle disposedon a construction line C-C′ that bisects the corner of the IC chip 510and equilateral sides that parallel the sides of the IC chip 510. In anexemplary embodiment, some crackstop elements of the corner crackstop500 may contact those portions of the crackstop (not shown) that areparallel to the sides of the IC chip 510.

Referring to FIGS. 6A and 6B, FIG. 6A illustrates a cross-section of thecorner crackstop 500 of FIG. 5 in a plane defined by the z-axis and theconstruction line C-C′, while FIG. 6B, by removing any overlyingintermetallic dielectric formed on the corner crackstop 500 thatoverlies the silicon layer 615 of the IC chip, illustrates a perspectivealong the construction line C-C′ from C to C′ that views successiveplanes defined by the z-axis and crackstop elements of each of the fourstepped layers, 501-504 of FIG. 5, which parallel the hypotenuse, H.

Referring to FIG. 6A, in the first layer 601 of the corner crackstop500, a first right-most crackstop element, comprising a metal cap 630centered over a via bar 620, may be disposed proximately to C of theconstruction line C-C′. A top view of the first right-most crackstopelement of the first layer 601 corresponds to 501 of FIG. 5. Referringto FIG. 6A, in the first layer 601 of the corner crackstop 500, a secondright-most corner crackstop element, comprising its metal cap 630centered on via bar 620, may adjoin the first right-most crackstopelement on a side surface that is distal from C. Because all of thecrackstop elements are of equal width, as measured along theconstruction line C-C′, the second right-most crackstop element willnecessarily parallel the first right-most crackstop element in the firstlayer 601. However, the length, as measured parallel to H, of the secondright-most crackstop element in the first layer 601, and its metal bar630 centered on via bar 620, may be greater than that of the firstright-most crackstop element because the equilateral sides of thetriangular area determine the length of the second right-most crackstopelement.

Similarly, a left-most nth crackstop element of the first layer 601 mayadjoin an (n−1)th crackstop element of the first layer 601. Theleft-most nth crackstop element, and its metal cap 630 centered on viabar 620, may have a greatest length, as measured parallel to H, of thecrackstop elements in the first layer 601 because it is closest to thelongest side, i.e., the hypotenuse, H, of the triangular area.

Referring to FIG. 6A, a right-most crackstop element of the second layer602, comprising a metal cap 630 centered over a via bar 620, may bevertically aligned over the second right-most crackstop element of thefirst layer 501 and have a length, as measured parallel to H, equal tothat of the second right-most crackstop element of the first layer 601.A top view of the right-most crackstop element of the second layer 602corresponds to 502 of FIG. 5. Similarly, a left-most crackstop elementof the second layer 602, and its metal cap 630 centered on a via bar620, may be vertically aligned over the left-most crackstop element ofthe first layer 601 and have a length equal to the greatest length ofthe crackstop elements in the triangular area.

Referring to FIG. 6A, a single crackstop element of the topmost or nthlayer, comprising a metal cap 630 centered on a via bar 620, may bevertically aligned over a left-most crackstop element of the (n−1)thlayer and its metal cap 630 centered on a via bar 620, and have a lengthequal to that of the greatest length of the crackstop elements. A topview of the single topmost or nth layer crackstop element corresponds to504 of FIG. 5. In fact, the left-most crackstop element, and its metalcap 630 centered on via bar 620, of every layer of the corner crackstopwill have a length equal to that of the greatest length of the crackstopelements in the corner crackstop 500.

Referring to FIG. 6A, the width, as measured along the construction lineC-C′, of each crackstop element may be equal to the width of the metalcap 630, and the width of via bar 620 may be less than that of the metalcap 630. Each metal cap 630 may comprise a metal and each via bar maycomprise a metal. None of the metal caps 630 and via bars 620 of any ofthe crackstop elements, formed in any of the layers of the cornercrackstop 500, may contact an electrical device within an active regionof the IC chip 510 of FIG. 5. A top surface of the corner crackstop 500may contact an overlying final passivation layer 635.

Referring to FIG. 6B, by removing any overlying intermetallic dielectricformed on the corner crackstop 500, the length, as measured parallel toH, of each metal cap 630 and via bar 620 for each of the exemplarylayers 601-604, which correspond to the stepped layers 501-504 of FIG.5, may be viewed from the perspective of C of the construction line C-C′toward the interior of the IC chip 510. The foremost surface, i.e.,closest to the corner of the IC chip 510, defined by the broad blacklines identifying the metal cap 630 and via bar 620 of layer 601,corresponds to foremost surface of 501, i.e., closest to the corner ofthe IC chip 510, and may have the smallest length, as measured parallelto H. Stepping away from the corner of IC chip 510 toward the center ofIC chip 510, the length of the uppermost crackstop elements of thesecond layer 602, defined by the broad black lines identifying the metalcap 630 and via bar 620, may increase. Similarly, stepping to the thirdlayer 603, the length of the uppermost crackstop elements of the thirdlayer 603 may increase relative to the length of the uppermost crackstopelements of the second layer 602. Finally, the length of the uppermostcrackstop elements of the topmost layer, e.g., layer 604, may have thegreatest length. Thus, the corner crackstop 500 may be characterized asforming a stepped chamfered surface, comprising the uppermost crackstopelements of each layer, disposed above the triangular area of a cornerregion of IC chip 510.

Although FIG. 5 shows the corner crackstop 500 comprising rectilinearstructures oriented parallel to the hypotenuse, H, of the triangulararea, the structures 501-504 may, instead, form outward-facing surfacesof a zigzag pattern comprising corner crackstop elements oriented eitherin parallel to the hypotenuse, H, or in parallel to the x-y axes of theIC chip 510, to help “break up” inwardly-directed crack forces.

FIG. 7 illustrates a top view, in the x-y plane, of another exemplaryembodiment of a corner crackstop 700 in a corner region of an IC chip710, where an overlying final passivation is removed. Referring to thecorner crackstop 700 of FIG. 7, a crackstop element of a second layer702 may overlie a part of a width, as measured along a construction lineC-C′, along the length, as measured parallel to H, of a crackstopelement of a first layer 701, a crackstop element of a third layer 703may likewise overlie a part of a width, as measured along theconstruction line C-C′, along the length, as measured parallel to H, ofthe crackstop element of the second layer 702, and so on, until thetopmost crackstop element of the topmost or nth layer may overlie a partof the width along the length of the crackstop element of an underlyinglayer. In the exemplary embodiment, the corner crackstop may comprise,for example, four stepped layers 701-704. The number of layers of thecorner crackstop 700 may equal the number of metallization layers formedwithin the active region of the IC chip 710, may span the height betweenthe underlying silicon layer and the final passivation layer, and mayrange from 3 to 12.

Referring to FIG. 7, the exemplary embodiment of corner crackstop 700may be formed within the triangular area, indicated by the dotted linesand proximate to the corner of IC chip 710. The triangular area, whichis disposed on a top surface of the silicon layer of the IC chip 710,may be defined by a right angle disposed on a construction line C-C′that bisects and is proximate to the corner of the IC chip 710, andequilateral sides that parallel the sides of the IC chip 710. In anexemplary embodiment, the corner crackstop 700 may contact thoseportions of a crackstop (not shown) that are parallel to the sides ofthe IC chip 710.

Referring to FIGS. 8A and 8B, FIG. 8A illustrates, by removing anyoverlying intermetallic dielectric formed on the corner crackstop 700 ofFIG. 7, a perspective along the construction line C-C′ from C to C′ thatviews successive planes defined by the z-axis and crackstop elements ofeach of the stepped layers 701-704 of FIG. 7 formed on the silicon layer815 of the IC chip 710, which parallel the hypotenuse, while FIG. 8Billustrates a cross-section of the corner crackstop 700 in the planedefined by the z-axis and the construction line C-C′.

Referring to FIG. 8A, by removing any overlying intermetallic dielectricformed on the corner crackstop 700, the length, as measured parallel toH, of each metal cap 830 and via bar 820 for each of the exemplarylayers 801-804, which correspond to the stepped layers 701-704 of FIG.7, may be viewed from the perspective of C of the construction line C-C′toward the interior of the IC chip 710. The foremost surface, i.e.,closest to the corner of the IC chip 710, defined by the broad blacklines identifying the metal cap 830 and via bar 820 of layer 801,corresponds to foremost surface of 701, i.e., closest to the corner ofthe IC chip 710, and may have the smallest length, as measured parallelto H. Stepping away from the corner of IC chip 710 toward the center ofIC chip 710, the length of the crackstop elements of the second layer802, defined by the broad black lines identifying the metal cap 830 andvia bar 820, may increase. Similarly, stepping to the third layer 803,the length of the crackstop elements of the third layer 803 may increaserelative to the length of the crackstop elements of the second layer802. Finally, the length of the crackstop elements of the topmost layer,e.g., layer 804, may have the greatest length. Thus, the cornercrackstop 700 may be characterized as forming a stepped chamferedsurface, comprising the crackstop elements of each layer, disposed abovethe triangular area of a corner region of IC chip 710.

Referring to FIG. 8B, a crackstop element of the first layer 801,comprising a metal cap 830 centered over a via bar 820, may be disposedon a top surface of the silicon layer 815 of the IC chip 710 of FIG. 7,proximate to C of the construction line C-C′ and parallel to thehypotenuse, H, of the triangular area. A crackstop element of the secondlayer 802, comprising a metal cap 830 centered over a via bar 820, maybe disposed more distally from C of the construction line C-C′ than thecrackstop element of the first layer 801 by a distance less than ½ w,i.e., one-half the width of a via bar 820. Similarly, the crackstopelements of each successive layer may be disposed more distally from Cof the construction line C-C′ by a distance of less than ½ w. Acrackstop element of the topmost or nth layer, e.g., the fourth layer,804, of the corner crackstop 700 of FIG. 7 may be more distally disposedfrom C of the construction line C-C′ by a distance of less than ½ wrelative to the underlying crackstop element of the (n−1)th layer, e.g.,the third layer, 803.

Referring to FIG. 8B, the width, as measured along the construction lineC-C′, of each crackstop element may be equal to a width of metal cap830, and the width of the metal cap 830 may greater than that of thewidth, w, of a via bar 820. Each metal cap 830 may comprise a metal andeach via bar 820 may comprise a metal. None of the metal caps 830 andvia bars 820 of any of the crackstop elements formed in any of thelayers of the corner crackstop 700 may contact an electrical devicewithin an active region of the IC chip 710. A top surface of the cornercrackstop 700 may contact an overlying final passivation layer 835.

Although FIG. 7 shows the corner crackstop 700 comprising rectilinearstructures oriented parallel to the hypotenuse, H, of the triangulararea, the structures 701-704 may, instead, form outward-facing surfacesof a zigzag pattern comprising corner crackstop elements oriented eitherin parallel to the hypotenuse, H, or in parallel to the x-y axes of theIC chip 710, to help “beak up” inwardly-directed crack forces.

The exemplary embodiment illustrated by FIG. 9 is similar to that ofFIG. 8B, and shows a cross-section in the plane defined by the z-axisand a construction line C-C′ of a corner crackstop including multiplecrackstop elements in each layer. Referring to FIG. 9, multiplecrackstop elements of the first layer 901, each comprising a metal cap930 centered over a via bar 920, may be disposed on a top surface of asilicon layer 915 of an IC chip, proximate to C of the construction lineC-C′ and each parallel to the hypotenuse, H, of a triangular area of theperimeter boundary region. Each of the multiple crackstop elements ofthe second layer 902 may be disposed more distally from C of theconstruction line C-C′ than the corresponding multiple crackstopelements of the first layer 901 by a distance less than ½ w, i.e.,one-half the width of a via bar 920 of one of the crackstop elements,where w is measured construction line C-C′. Similarly, each of themultiple crackstop elements of each successive layer may be disposedmore distally from C of the construction line C-C′ than thecorresponding multiple crackstop element of the underlying layer by adistance of less than ½ w. Each of the multiple crackstop elements ofthe topmost or nth layer, e.g., the fourth layer, 904, of the cornercrackstop may be more distally disposed from C of the construction lineC-C′ by a distance of less than ½ w relative to the underlyingcorresponding multiple crackstop element of the (n−1)th layer, e.g., thethird layer, 903.

Referring to FIG. 9, the width, as measured along the construction lineC-C′, of each of the multiple crackstop elements, may be equal to awidth of metal cap 930, and the width of the metal cap 930 may begreater than the width, w, of a via bar 920. Each metal cap 930 maycomprise a metal and each via bar 920 may comprise a metal. None of themetal caps 930 and via bars 920 of any of the crackstop elements formedin any of the layers of the corner crackstop may contact an electricaldevice within an active region of the IC chip. A top surface of thecorner crackstop may contact an overlying final passivation layer 935.

Although the cross-section of FIG. 9 assumes that each of the multiplecrackstop elements of each layer, e.g., 901-904, forms a beveledrectilinear structure that parallels the hypotenuse, H, of thetriangular area, the overlying structures of layers 901-904 may,instead, form one or more outward-facing surfaces of a zigzag patterncomprising corner crackstop elements oriented either in parallel to thehypotenuse, H, or in parallel to the x-y axes of the IC chip, to help“break up” inwardly-directed crack forces.

FIG. 10 illustrates a flowchart that depicts a method of making anexemplary embodiment of a corner crackstop. Process 1010 indicates thata plurality of n layers is formed on a silicon layer of an IC chipwithin a perimeter boundary region of a corner of the IC chip. Eachlayer in the process includes a number of crackstop elements, in whicheach crackstop element has the same width and includes at least onemetal cap centered on a corresponding at least one via bar, which has awidth, w. The process 1020 defines the perimeter boundary region on atop surface of the silicon layer of the IC chip that comprises atriangle. The triangle includes a right angle that is disposed on abisector of the corner angle of the IC chip and equilateral sides thatare parallel to the sides of the IC chip, where the right angle isproximate to the corner relative to the hypotenuse of the triangle. Theprocess 1030 forms a crackstop element of a first layer, which isdisposed proximately to the right angle of the triangle, oriented inparallel to the hypotenuse, and having a smallest length determined andlimited by the equilateral sides of the triangle. The process 1040 formsa crackstop element of the second layer, which is disposed more distallyfrom the right angle than the crackstop element of the first layer by adistance equal to the width of a via bar, w, or by a distance less than½ w, along the bisector, oriented parallel to the hypotenuse, and havinga greater length than the smallest length, which is determined andlimited by the equilateral sides of the triangle. The process 1050 formsa crackstop element of an nth layer that is more distally disposed fromthe right angle of the triangle than a crackstop element of a (n−1)layer by the distance equal to the width of a via bar, w, or by thedistance less than ½ w, along the bisector, oriented in parallel to thehypotenuse, and having a greatest length limited by the equilateralsides of the triangle.

The resulting integrated circuit chips can be distributed by thefabricator in raw wafer form (that is, as a single wafer that hasmultiple unpackaged chips), as a bare die, or in a packaged form. In thelatter case the chip is mounted in a single chip package (such as aplastic carrier, with leads that are affixed to a motherboard or otherhigher level carrier) or in a multichip package (such as a ceramiccarrier that has either or both surface interconnections or buriedinterconnections). In any case the chip is then integrated with otherchips, discrete circuit elements, and/or other signal processing devicesas part of either (a) an intermediate product, such as a motherboard, or(b) an end product. The end product can be any product that includesintegrated circuit chips, ranging from toys and other low-endapplications to advanced computer products having a display, a keyboardor other input device, and a central processor.

For purposes herein, a “semiconductor” is a material or element that mayinclude an implanted impurity that allows the material to sometimes be aconductor and sometimes be an insulator, based on electron and holecarrier concentration. For purposes herein, a “dielectric” is a relativeterm that means a material or element that allows substantially less(<95%) electrical current to flow than does a “conductor.” Thedielectrics (insulators) mentioned herein can, for example, be grownfrom either dry oxygen ambient or steam and then patterned.Alternatively, the dielectrics herein may be formed from any of the manycandidate high dielectric constant (high-k) materials, including but notlimited to silicon nitride, silicon oxynitride, a gate dielectric stackof SiO2 and Si3N4, and metal oxides like tantalum oxide. The thicknessof dielectrics herein may vary contingent upon the required deviceperformance. The conductors herein may be one or more metals, such astungsten, hafnium, tantalum, molybdenum, titanium, or nickel, or a metalsilicide, any alloys of such metals, and may be deposited using physicalvapor deposition, chemical vapor deposition, or any other techniqueknown in the art.

When patterning any material herein, the material to be patterned can begrown or deposited in any known manner and a patterning layer (such asan organic photoresist) can be formed over the material. The patterninglayer (resist) can be exposed to some form of light radiation (e.g.,patterned exposure, laser exposure, etc.) provided in a light exposurepattern, and then the resist is developed using a chemical agent. Thisprocess changes the characteristic of the portion of the resist that wasexposed to the light. Then one portion of the resist can be rinsed off,leaving the other portion of the resist to protect the material to bepatterned. A material removal process is then performed (e.g., plasmaetching, etc.) to remove the unprotected portions of the material to bepatterned. The resist is subsequently removed to leave the underlyingmaterial patterned according to the light exposure pattern.

In addition, terms such as “right”, “left”, “vertical”, “horizontal”,“top”, “bottom”, “upper”, “lower”, “under”, “below”, “underlying”,“over”, “overlying”, “parallel”, “perpendicular”, etc., used herein areunderstood to be relative locations as they are oriented and illustratedin the drawings (unless otherwise indicated). Terms such as “touching”,“on”, “in direct contact”, “abutting”, “directly adjacent to”, etc.,mean that at least one element physically contacts another element(without other elements separating the described elements).

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the embodiments.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The description of the embodiments herein have been presented forpurposes of illustration and description, but is not intended to beexhaustive or limited to the embodiments in the form disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of theembodiments. The embodiment was chosen and described in order to bestexplain the principles of the embodiments and the practical application,and to enable others of ordinary skill in the art to understand theembodiments for various embodiments with various modifications as aresuited to the particular use contemplated.

What is claimed is:
 1. A corner crackstop comprising: a plurality of nmetallization layers formed on a silicon layer of an integrated circuit(IC) chip above a perimeter boundary region of a corner of said IC chip,said perimeter boundary region comprising a triangle, a right angle ofsaid triangle being disposed on a bisector of said corner of said ICchip, equilateral sides of said triangle being parallel to sides of saidIC chip, and a hypotenuse of said triangle being orthogonal to saidbisector; and a crackstop element disposed within each of said nmetallization layers, each crackstop element being longitudinallyoriented in parallel to said hypotenuse, being limited in length by saidequilateral sides, and rising step-wise with each of said nmetallization layers along said bisector from said right angle, acrackstop element of a first layer being disposed proximately to saidright angle and having a smallest length limited by said equilateralsides; a crackstop element of a second layer being disposed moredistally from said right angle than said crackstop element of said firstlayer, partially overlapping and contacting said crackstop element ofsaid first layer, and having a greater length limited by saidequilateral sides; and a crackstop element of an nth layer beingdisposed yet more distally from said right angle along said bisectorthan said crackstop element of an (n−1)th layer, partially overlappingand contacting said crackstop element of said (n−1)th layer, and havinga greatest length limited by said equilateral sides.
 2. The cornercrackstop of claim 1, each crackstop element including a via bar and ametal cap, said via bar being formed in an intermetallic dielectriclayer of each of said n metallization layers, being longitudinallyoriented in parallel to said hypotenuse and having a width, w, measuredalong said bisector, and said metal cap being formed in a patternedmetal layer of each of said n metallization layers, being longitudinallyoriented in parallel to said hypotenuse, having a width greater thansaid width, w, of said via bar and being centered along said bisectorover said via bar.
 3. The corner crackstop of claim 2, each successivelyhigher crackstop element of each successively higher of said nmetallization layers overlapping by a distance of less than ½ w alongsaid bisector from a center of a lower crackstop element.
 4. The cornercrackstop of claim 3, said metal cap and said via bar of each crackstopelement, formed in each of said n metallization layers within saidperimeter boundary region, not contacting an electrical device in anactive region of said IC chip.
 5. The corner crackstop of claim 1, eachcorner crackstop element of said n metallization layers contacting aportion of another crackstop that is parallel to sides of said IC chip.6. The corner crackstop of claim 1, a plurality of corner crackstopelements corresponding to said plurality of said n metallization layersproximate to said corner region of said IC chip, forming a steppedchamfered outward-facing surface disposed between side surfaces andbetween a top surface and said silicon layer of said corner region ofsaid IC chip.
 7. A method of making a corner crackstop comprising:forming a plurality of n metallization layers on a silicon layer of anintegrated circuit (IC) chip above a perimeter boundary region of acorner of said IC chip, said perimeter boundary region comprising atriangle, a right angle of said triangle being disposed on a bisector ofsaid corner of said IC chip, equilateral sides of said triangle beingparallel to sides of said IC chip, and a hypotenuse of said trianglebeing orthogonal to said bisector; and forming a crackstop elementdisposed within each of said n metallization layers, each crackstopelement being longitudinally oriented in parallel to said hypotenuse,being limited in length by said equilateral sides, and rising step-wisewith each of said n metallization layers along said bisector from saidright angle, a crackstop element of a first layer being formedproximately to said right angle of said triangle and having a smallestlength limited by said equilateral sides, a crackstop element of asecond layer being formed more distally from said right angle than saidcrackstop element of said first layer, partially overlapping andcontacting said crackstop element of said first layer, and having agreater length limited by said equilateral sides, and a crackstopelement of an nth layer being formed yet more distally from said rightangle along said bisector than said crackstop element of an (n−1)thlayer, partially overlapping and contacting said crackstop element ofsaid (n−1)th layer, and having a greatest length limited by saidequilateral sides.
 8. The method of claim 7, further comprising forminga final passivation layer on a top surface of said nth layer of saidcorner crackstop and on an active region of said IC chip.
 9. The methodof claim 7, each crackstop element including a via bar and a metal cap,said via bar being formed in an intermetallic dielectric layer of eachof said n metallization layers, being longitudinally oriented inparallel to said hypotenuse and having a width, w, measured along saidbisector, and said metal cap being formed in a patterned metal layer ofeach of said n metallization layers, being longitudinally oriented inparallel to said hypotenuse, having a width greater than said width, w,of said via bar and being centered along said bisector over said viabar.
 10. The method of claim 9, each successively higher crackstopelement of each successively higher of said n metallization layersoverlapping by a distance of less than ½ w along said bisector from acenter of a lower crackstop element.
 11. The method of claim 9, saidmetal cap and said via bar of each crackstop element, formed in each ofsaid n metallization layers within said perimeter boundary region, notcontacting an electrical device in an active region of said IC chip. 12.The method of claim 7, each corner crackstop element of said nmetallization layers contacting a portion of another crackstop that isparallel to sides of said IC chip.
 13. The method of claim 7, aplurality of corner crackstop elements corresponding to said pluralityof said n metallization layers proximate to said corner region of saidIC chip, forming a stepped chamfered outward-facing surface disposedbetween side surfaces and between a top surface and said silicon layerof said corner region of said IC chip.
 14. A method of making a cornercrackstop comprising: forming a plurality of n metallization layers on asilicon layer of an integrated circuit (IC) chip above a perimeterboundary region of a corner of said IC chip, said perimeter boundaryregion comprising a triangle, a right angle of said triangle beingdisposed on a bisector of said corner of said IC chip, equilateral sidesof said triangle being parallel to sides of said IC chip, and ahypotenuse of said triangle being orthogonal to said bisector; andforming a crackstop element disposed within each of said n metallizationlayers, each crackstop element being longitudinally oriented in parallelto said hypotenuse, being limited in length by said equilateral sides,and rising step-wise with each of said n metallization layers along saidbisector from said right angle, a crackstop element of a first layerbeing formed proximately to said right angle of said triangle and havinga smallest length limited by said equilateral sides, a crackstop elementof a second layer being formed more distally from said right angle thansaid crackstop element of said first layer, partially overlapping andcontacting said crackstop element of said first layer, and having agreater length limited by said equilateral sides, and a crackstopelement of an nth layer being formed yet more distally from said rightangle along said bisector than said crackstop element of an (n−1)thlayer, partially overlapping and contacting said crackstop element ofsaid (n−1)th layer, and having a greatest length limited by saidequilateral sides; and forming a final passivation layer on a topsurface of said nth layer of said corner crackstop and on an activeregion of said IC chip.
 15. The method of claim 14, each crackstopelement including a via bar and a metal cap, said via bar being formedin an intermetallic dielectric layer of each of said n metallizationlayers, being longitudinally oriented in parallel to said hypotenuse andhaving a width, w, measured along said bisector, and said metal capbeing formed in a patterned metal layer of each of said n metallizationlayers, being longitudinally oriented in parallel to said hypotenuse,having a width greater than said width, w, of said via bar and beingcentered along said bisector over said via bar.
 16. The method of claim15, each successively higher crackstop element of each successivelyhigher of said n metallization layers overlapping by a distance of lessthan ½ w along said bisector from a center of a lower crackstop element.17. The method of claim 15, said metal cap and said via bar of eachcrackstop element, formed in each of said n metallization layers withinsaid perimeter boundary region, not contacting an electrical device inan active region of said IC chip.
 18. The method of claim 14, eachcorner crackstop element of said n metallization layers contacting aportion of another crackstop that is parallel to sides of said IC chip.19. The method of claim 18, a plurality of corner crackstop elementscorresponding to said plurality of said n metallization layers proximateto said corner region of said IC chip and said portion of said anothercrackstop that is parallel to said sides of said IC chip, separatingsaid active region of said IC chip from said perimeter boundary region.20. The method of claim 14, a plurality of corner crackstop elementscorresponding to said plurality of said n metallization layers proximateto said corner region of said IC chip, forming a stepped chamferedoutward-facing surface disposed between side surfaces and between a topsurface and said silicon layer of said corner region of said IC chip.